Engine performance modification or tuning kit

Abstract

A performance modification / tuning kit for an internal combustion engine of the type comprises a kit control unit. An electrical sensor is adapted to detect the opening and closing signals of a control line to one of the injectors of the engine and connected through a sensor line to the control unit. An input receives the signal from a pressure sensor of the common fuel rail of the engine and an output report a generated pressure signal to the engines ECU. A selectively changeable modification map, comprising modification values for a range of different engine speeds and fuel loads demanded by the ECU is used by the kit control unit to generate the generated pressure signal. That is generated in dependence upon the value in the modification map for the engine fuel load Q currently demanded by the ECU and the engine speed currently pertaining from time to time.

Description

[0001]This invention relates to a tuning kit for modifying the performance of common rail internal combustion engines, in particular, diesel engines.BACKGROUND[0002]A common rail diesel (or petrol) engine has a manifold (the common rail) containing fuel that is under pressure (which pressure is monitored by an engine management unit (ECU)) and a number of injectors supplied by the manifold and connected to each cylinder of the engine. The ECU also controls the injectors and opens each in defined sequence and for controlled periods of time to admit fuel into the engine at the appropriate point(s) of the engine 4-stroke cycle.[0003]The volume of fuel injected in any given engine cycle is obviously a function of the time period that an injector is open during that cycle and the pressure pertaining in the manifold. In fact, it is largely directly proportional to the time, and approximately proportional to the square root of the fuel pressure. The ECU controls the amount of fuel to be in...

AI Technical Summary

Benefits of technology

[0034]Thus, the second effect of the kit according to the invention is that the fuel actually to be delivered at a given demanded fuel load can be proportionally adjusted, as may be required and dependent on the user's purpose. In one case, the amount of fuel delivered may be increased, to enhance engine performance. In another case, it may be reduced, to degrade engine performance, or perhaps to allow another fuel to be also employed

[0040]A combination of effects may be employed in some situations. For example, diesel engines in commercial vehicles work best at low speed with high torques. Thus it is feasible to arrange for fuel delivery to be increased at high loads and low speeds, enhancing low speed torque of the engine, whereas at high speed for the fuel delivery to be reduced encouraging the driver to change gear and maintain operation of the engine at the low-speed / high-torque end of the engine spectrum.

[0049]Thus the present invention allows a range of different modifications to be effected. One such arrangement is to boost the performance of a vehicle. As already mentioned, most car manufacturers, particularly if they are concerned that their vehicles meet challenging emissions targets at all operating conditions, employ a fuel delivery map that is conservative in the sense that there is always excess of air entering the chamber whereby complete combustion can better be assured. This enables performance simply to be enhanced by increasing the balance of fuel and air in favour of a closer stoichiometric ratio. Indeed, a benefit of the invention is that, if emission levels are seen to be excessive at certain loads or speeds, once the kit has been installed, it is possible to adapt the modification map so that areas of the map that result in unacceptable emissions can be adjusted. This advantage is also useful in situations where the modification map is so radical at certain engine speeds and loads that it results in a fault condition being diagnosed at certain points of the map by the ECU, which then puts the engine into an error mode of operation. Such radical points of the modification map can be selectively eliminated so that the fault conditions are not initiated.

[0059]In the case of a piezo driven valve, the start of the opening signal is taken to be when the voltage value increases more than x% above the base line. However, return of the voltage value to the base line does not trigger a closing signal. The closing signal is taken to be when the voltage value decreases to more than y% below the base line. In this case, y is generally the same as x, but they can be different. Of course, in both cases the moment of opening or closing is not the issue. The purpose is to be consistent between different opening and closing events and to reflect accurately a value that is always in the same proportion to the actual opening times, whatever they are in actuality. Thus an actual opening time of 3.00 ms may be recorded by the unit as 2.99 ms but this is of no consequence to the control unit, provided the “inaccuracy” is accurately consistent. Another aspect of the kit is the ability to deal with latency in the opening of the injectors. However, this is within the ability of the skilled person.

Problems solved by technology

However, it is apparent that merely by increasing the ratio of fuel to air, the performance of modern engines can be affected.

A problem with this method is that engine mapping is frequently reloaded by garages when they complete service schedules for a vehicle.

A problem with such a unit is that it is generally not possible to make fuel adjustments at specific engine speeds or loads.

Moreover, the inability to specify under what conditions an increase or decrease in fuel should occur can trigger engine management fault codes or cause drivability issues.

This limits the level of fuel adjustment that can be made.

For example, existing kits that under-report the fuel pressure by, say, 10% or 20%, may be satisfactory at some engine performance levels, but, at others, such substantial change may cause an engine error code to be generated.

Indeed, at low engine loads it is seldom desirable to change the fuel quantity injected.

However, no specific scheme or algorithm is proposed as such.

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